Towing winch control system

ABSTRACT

A towing winch control system in which the winch for the towing cable is driven through a slipping clutch to apply a substantially constant tension to the towing cable, and a position sensor and a tensiometer are operated to control the length of the tow cable between the towing winch and the object being towed and to limit the load on the cable to prevent parting of the cable.

United States Patent Barron [451 Apr. 2, 1974 TOWING WINCH CONTROLSYSTEM 3,596,070 7 1971 McCool 254 173 R x 4 82 9 1 [75] Inventor:Charles D. Barron, Huntmgton g gz J gs? I i: Beach, m- 3,612,486. 101971 Martin 254 172 17 1 Assigneer y J g Beach, FORElGN PATENTS 0RAPPLICATIONS Cahf- 1,159,229 11/1956 Germany 254 172 22 il O 6 19721,138,908 11/1959 Germany 254/173 864,182 3/1961 Great Britain...254/173 [211 App]. No.: 295,758 646,279 4/1933 Germany 254/173 RelatedUS. Application Data 1,294,078 2/1969 Germany 254/173 [63] Continuationof Ser. No. 110,695, Jan. 28, 1971, primary Examiner RichaI-d Aegerterabandoned Assistant ExaminerH. S. Lane Attorney, Agent, or Firm-DonaldW. Banner [52] U.S. C1. 254/173 R, 254/187 R [5 Int. .1 [58] Field ofSearch 254/172 R, 173 B, 185 R, 1

v A towmg wmch control system in WhlCh the wlnch for 254/173 R, 187 R,175.7

the towlng cable 1s dr1ven through a slipping clutch to [561 121123 22221221 9,:-

e, a a pos sen a 10m e UNITED STATES PATENTS ated to control the lengthof the tow cable between 2,275,953 Fl'lSCh the towing winch and theobject being towed and to 2,443,028 6/1948 Edwards'" 254/172 limit theload on the cable to prevent parting of the 3,189,196 6/1965 Carl et a1.214/14 cable 3,289,967 12/1966 Robinson 254/172 X 3,507,478 4/1970 15Claims, 6 Drawing Figures Lewis 254/1757 PATENTEBAPR 21am 3.801.071

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PATENTED APR 2 I974 SHEET 3 BF 4 INVENTOR (H/45665 0. e eeo/v TOWINGWINCH CONTROL SYSTEM This application isa continuation of applicationSer. No. 110,695, filed Jan. 28, 1971, now abandoned.

BACKGROUND OF THE INVENTION The towing of a vessel to sea, such as welldrilling barges, cargo barges, or, indeed any vessel, by a tug or othertowing vessel, poses problems which are difficult of solution,Heretofore, the towing cable by which the towing vessel tows the towedvessel has been relied upon to compensate for changes in load on thecable due to changes in tidal, wave, or wind action on the vessels, and,as a result, an extremely long run of cable or line has been employed.The cable sags between the vessels, generally beneath the water andprovides a long arcuate cable section which can be more or lesstensioned as the towing vessel and the towed vessel experience differentinfluences of tide, waves, or wind, or combinations thereof.

Such long tow lines or cables make control of the towed vessel verydifficult, particularly when entering or navigating narrow channels orwaterways. A heavy barge may require a length of tow line or cable onthe order of one quarter mile, for example, to afford a safe bow in theline or cable, whereby the towing and towed vessels may reactdifferently to different influences without parting the tow line orcable. A typical problem in this connection involves the oppositereactions caused by the towed vessels tending to slow down when on thetrailing slope ofa wave and the towing vessel's tending to acceleratewhen picked up by the forward slope ofa wave. Such long tow lines orcables also produce a navigational hazard, particularly, when visibilityis poor, and the pilot of another vessel may not be aware of theexistence of the tow line, due to his inability to see the towed vessel,or, perhaps, either ves-' sel.

Ordinarily, the towing line or cable is on a towing winch and is playedoff as may be required by the relative conditions of the sea and theweight of the towed vessel. When desired, the winch is operated to pullin the line or cable to shorten the distance between the two vessels.However, if, due to wave, tide or wind influence on the vessels, theline is over loaded it may part, allowing the towed vessel to then driftfree, with potentially dangerous results.

SUMMARY OF THE INVENTION The present invention provides a towing winchsystem which obviates the problems and hazards of the above-describedtowing practices.

More particularly, the present invention is a towing winch system whichmay be employed on a towing vessel to tow another vessel, or string ofvessels, in a more closely adjacent relation than has been practicalheretofore.

The towing winch system, in general, involves a winch adapted to bedriven by a power source through a clutch which is capable of constantlyslipping to apply a substantially constant tension on the towing line orcable. When the load on the line or cable increases above a pre-setcapacity. the line or cable will be stripped from the winch, but when,the tension is thereafter reduced the line or cable will be rewound bythe winch until the towed vessel is in the pre-selected spaced relationto the towing vessel.

In accomplishing the foregoing, a position sensor and a tensiometer areengaged with and operated by the tow line or cable to control the slipclutch so as to maintain the tension on the line or cable and tomaintain the relative positions of the vessel, so long as differentinfluences on the vessels permit the maintenance of the relativepositions of the vessels, and to re-establish the tension on the line orcable and the relative positions of the vessels when the influences onthe vessels, or either of them, permit.

Constant tension winches, driven by a fluid pressure actuated slipclutch are well known,'as exemplified in United States Letters PatentNo. 3,373,972, dated March 19, 1968. Preferably, however,'to effectbetter cooling of the slip clutch with resultant improved efficiency,the clutch may be cooled as disclosed in the pending application forUnited States Letters Patent of C. D. Barron, Ser. No. 19,601, filedMar. 16, 1970. The position sensor referred to above is adapted to causea change in the fluid pressure acting on the slip clutch, and ispreferably made in accordance with the disclosure of the pendingapplication for United States Letters Patent of C. D. Barron, Ser. No.19,564, filed Mar. 16, 1970.

This invention possesses many other advantages, and has other purposeswhich may be made more clearly apparent from a consideration of a formin which it may be embodied. This form is shown in the drawingsaccompanying and forming part of the present specification. It will nowbe described in detail, for the purpose of illustrating the generalprinciples of the invention; but it is to be understood that suchdetailed. description is not to be taken in a limiting sense, since thescope of the invention is best defined by the appended claims. In thisconnection, while the invention is herein disclosed as beingincorporated in a towing winch system, it will be understood that theinvention is applicable to other dynamic systems in which the tension ona line and the position of a line must be controlled or adjusted toprevent overloading of the line and to reposition a load in response tochanges in load condition.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective, generallyillustrating a towing vessel and a towed barge to which the towing winchcontrol system of the invention is applied;

FIGS. 2a and 2b, together constitute a diagrammatic illustration of thetowing winch control system, FIG. 2b constituting a downwardcontinuation of FIG. 2a;

FIG. 3 is a longitudinal section through a computing relay or pressuretransmitter employed to vary the drive of a slip clutch in response tovariations in the load conditions on the towing winch line;

FIG. 4 is a longitudinal section through a line position sensing devicefor varying a pressure signal supplied to the computer of FIG. 3, inresponse to changes in position of the towing winch line; and

FIG. 5 is a view partly in elevation and partly in longitudinal section,showing a slip clutch assembly for driving the towing winch.

DESCRIPTION OF THE PREFERRED EMBODIMENT As seen in the drawings, withreference first to FIG. 1, a towing vessel or tug boat V isv shown ashaving a towing winch W from which a tow cable or line L extendssternward for connection to a towed vessel or barge B.

While a rock barge is shown as illustrative, it will be understood thatthe problem of overload on. a towing line L exists in any similarsituation involving a towed vessel or barge, such as, for examples, anoffshore well drilling platform, a disabled ship, or the like.

The towing vessel or tug is shown as having the winch W disposedabove-deck, for clarity, and a suitable drive or motor. source M isshown below-deck, but as a practical matter, it may be preferred thatthe entire apparatus or any portion thereof be located below deck, withthe cable or line L passing through a fairlead or guide at the stern ofthe vessel V.

More particularly, the illustrative drive M includes a suitable driveconnection in the form of a chain adapted to effect rotation of acounter shaft 11 through a slip clutch assembly C, which, as is moreparticularly seen in FIG. 5 and described hereinafter, is adapted totransmit torque to the shaft 11 under the control of the control systemof the invention, whereby to limit the tension on the line L and toadjust the relative positions of the towing vessel V and the barge B.Thus, a drive connection, say the illustrative chain drive 12 providesmeans for applying torque to the drum 13 of the winch W, whereby theline L will be pulled in if the selected line tension overcomes the loadof the barge B, but the line L may be stripped from the drum 13 if thebarge exceeds the pre-set line tension. Associated with the line L aresensing means TP, incorporated in the system and adapted, as will belater described, to sense the load or tension on the line L and to sensechanges in position of the line L so as to effect control of the line.

Referring to FlG. 2a, the sensing means T? is gener ally shown 'tocomprise a typical hydraulic tensiometer l5 and a position senser 16.The tensiorneter 15 is adapted to be applied to the line L in such amanner that the line engages and extends between a pair of spacedrollers 17 and 19 which are rotatable on shafts -l9 and 20,respectively, supported in a frame 21. A third roller 22 engages theline L between the rollers 17 and 18 to deflect the intermediate portionof the line, the roller 22 being carried on a shaft 23 which is mountedfor movement relative to the frame 21, whereby such movementis appliedto the hydraulic sensing unit 24, to produce a hydraulic signal themagnitude of which is a function of tension on the line L. Such devices15 are well known and require no further description herein. An exampleof such a line tension no responsive device is the Tensiometer ModelUD12 of Martin-Decker Corp., of Santa Ana, Calif. The position sensorunit 16 of the sensing means '1'? is more particularly illustrated inFIG. 4 and will be latter described.

ln order to control the speed 'at which the line L may change position,speed control means including a tachometer signal generator 25 isadapted to be driven by the winch drum 13 to supply a variable signal toan lsst n sqm a qi st 55a! QE..MQQ.1II1Q electro-pneumatic, transducerof Conoflow Corporation of Blackwood, NJ. The output from the hydraulicunit 15, the position sensor 16 and the transducer 26 are compared bycomputer means 27, the details of which are shown in FIG. 3, to controlthe clutch C, as will be more fully described below.

The clutch C, as best seenin FIG. 5, is associated with an end 37 of thecounter shaft 11, and the drive chain 10 engages a sprocket 50 which isrevolvable relative to the shaft end 37 on bearings 52. Affixed to thesprocket 50, is a disc 54 which is in turn affixed by fasteners 55 tothe outer periphery of the back-up plate 56 of the slip clutch means C.i

This slip clutch means C includes an outer annular body 57 to which anannular flange 58 is connected by fasteners 59 in opposed relation tothe plate 56. Internally thereof, the body 57 has a splined connection60 with the outer periphery of an axially shiftable clutch pressureplate 61. Between the clutch plates 56 and 61 is a clutch friction disc62 having friction facing 63 on opposite sides thereof and having, as at64, a splined connection with a hub 65 which is disposed upon the shaftend 37 and is keyed thereto by a key 66. Thus, rotation from thesprocket 50 will be transmitted to the tensioning hoist shaft 11 whenthe slip clutch means C is engaged to transmit rotation from the clutchbody 57 and its plates 56 and 61 to the friction disc 62.

Engagement of the slip clutch means C is accomplished by an annularexpansible actuator tube 67 having an air inlet 68. The actuator tube 67engages an annular body of insulating material 69 interposed between thetube 67 and the clutch pressure plate 61. Each of the clutch plates 56and 61 has a number of annular, radially spaced and concentric coolantpassages 56a and 61a to which a coolant is supplied to dissipate theheat of friction caused by slippage of the clutch C. These passages 56aand 610 are defined respectively between the clutch plates and a weardisc 56b carried by the plate 56 and a wear disc 61b carried by theplate 61, the friction material on the friction disc 62 being engagedwith the wear discs 56b, 61b.

Such cooled, slip clutches are well known, and generally are providedwith a coolant circulating system including a stationary coolantconnector 71 through which coolant flows to and from a rotary connector72 which is connected, as by fasteners 72a, to the clutch flange 58 andwhich has conduit means 73 for supplying coolant to the passages 56a and61a, as well as conduit means for the return flow of coolant to theconnector 71 and thenceto a heat exchanger. Preferably, in order to moreeffectively cool the clutch, it is constructed in accordance with theaforementioned application for patent. lnaddition, the rotary connector72 provides a connection for air conduit means 74 which leads to the airinlet 68 for the clutch actuator tube 67 from a stationary air inletfitting 75. As is well known, the torque transmitting capacity of suchslip clutches varies withthe pressure of air in the actuator tube 67.

Thus, the tension applied to the line L will be determined by themagnitude of the air pressure supplied to the actuator tube 67 throughthe coupling 75 under the control of the computing relay 27, as will bemore fully described below.

The preferred line position sensing unit 16, of the sensing meant TP, isshown in greater detail in FIG. 4, and is more specifically disclosed inthe aforementioned pending patent application. It comprises an elongatedhousing 81 having at one end a closure or cap 82 and having at the otherend an assembly which provides an air inlet or supply port 84, an outlet85 for a controlled air pressure signal, a port 86 for bias pressurefluid, and a port 87 communicating with the atmosphere.

Included within the assembly are actuator means generally denoted at 88,fluid pressure responsive piston means 89 operatively connected to theactuator means 88, orifice means 90 operable in response to theapplication of fluid pressure to the piston means 89 and to theapplication of force from the actuator means 88 for opening and closingthe orifice means 90, and combined inlet and outlet valve means 91 forcontrolling the flow of air from the supply port 84 to the output port85 and for controlling the exhaust of air from the outlet port to theatmosphere through the port 87.

In general, it is the purpose of the position sensing pneumatic controldevice to regulate the output signal pressure to a constant value whichis determined by the net force applied to the piston means 89, wherebythe orifice means 90 is either opened or closed for a period sufficientto balance the piston means 89, so that the pressure drop through theorifice means 90 remains constant, resulting in a constant output signalpressure at the port 85 which leads to the computer relay 27, as will belater described.

More particularly, the actuator means 88 comprises a shaft 92 whichextends longitudinally of the housing 81 and has an end 93 which extendsaxially from the end cap 82 through a suitable bearing 94 and a suitableseal 95. Disposed upon the shaft 92 within the housing 81 is a springseat 96 having a reduced central section 97 on which is piloted theupper end of a coiled compression spring 98. The shaft 92 is threaded asat 99, and the spring seat 96 and the reduced pilot portion 97 thereofare complementally threaded, whereby rotation of the shaft 92 willeffect longitudinal movement of the spring seat 96 on the shaft, sincethe seat 96 is held against rotation by a key 100 carried thereby andextending into a lateral slot 101 in the housing 81. At its inner endthe spring 98 seats on a spring seat 103 having a reduced pilot portion104. This spring seat 103 is connected by fasteners 105 to the circularupper body portion 106 of the piston 107 of the piston means 89, theseat 103 and the body 106 being held in axially spaced relation bytubular spacers 108 interposed therebetween and through which thefasteners 105 extend. The lower end of the shaft 92 extends through theseat 103 and is journalled in a bearing 109 which is mounted in asupporting spider 110 having circumferentially spaced openings 111 toaccommodate the spacers 108, whereby the piston means 89 is axiallymovable.

The assembly also comprises, in addition to the spider 110, an annularspacer 112, an annular cylinder 113 for the piston 107 and an annularcylinder 114 which houses a piston 115, an annular body 116 containingthe nozzle means 90, and an end member 117. The spider 110, spacer 112,cylinders 113 and 114, annular body 116, and end member 117 areinterconnected together and to the cylindrical body 81 by tiebolts orthe like, requiring no illustration.

Between the spacer 112 and the cylinder 113 is clamped the outermarginal portion of a diaphragm 119, and between the cylinder 113 andthe cylinder 114 is clamped the outer marginal portion of anotherdiaphragm 120. Still another diaphragm 121 has its outer marginalportion clamped between the cylinder 114 and the annular body 116. Inthe illustrative embodiment. the body portion 106 of the piston 107, as

well as the piston 107 and the piston are interconnected by a stem 122having an enlarged head 123 at one end which clamps the inner peripheryof the diaphragm 121 against the adjacent portions of the piston 1 15,and a nut 124 is threaded onto the other end of the stem 122 toeffectively clamp the piston 117, including its upper body portion 106,and the piston 107 together. The inner periphery of the diaphragm 119 islike-wise clamped between the upper body portion 106 and the piston 107,and the inner periphery of the diaphragm is clamped between the piston107 and the piston 115. Thus, the piston means 89 comprises both thepiston 107 and the piston 115. More particularly, the piston 107 has anenlarged portion 125 which is exposed to the pressure in a chamber 126provided in the cylinder 113 between the diaphragms 119 and 120. Thepiston 115 is exposed to the pressure in a chamber 127 provided in theannular body 116 across substantially the entire cross-sectional area ofthe piston 115. Within the cylinder 114, the piston 115 is disposed in achamber 128 which is vented to the atmosphere through radial ports 129.

lnterposed between the annular body 116 and the end member 117, andclamped at its outer margin is a double diaphragm assembly including anupper diaphragm 130 and a lower diaphragm 131 spaced apart by an outermaterial spacer 132 in which is formed one or more of the radial 'outletports 87, previously referred to, which communicate the space betweenthe diaphragms 130 and 131 with the atmosphere. In the annular body 116above the upper diaphragm 130 is a chamber 134 and centrally of the body116 is a threaded bore having therein a nozzle 136, the port throughwhich communicates with the chamber 134, and the outlet of which isopposed by a nozzle seat 137 suitably carried by the lower end of thestem 122. Air is supplied to the chamber 134 and thence to the nozzle136 from the supply port 84 through a passage 138 which extends throughthe margin of the diaphragms 130 and 131 and the spacer 132 and connectswith a passage 139 leading into the chamber 134. Disposed in the passage139 is a flow restrictor 140 having a reduced passage therethrough'Thisflow restrictor is replaceable through an opening in thebody 116 whichis closed by a threaded closure plug 141. At the outer side of thediaphragm 131 in the end member 127 is a chamber 142 which communicateswith the output port 85. The output port 85 also communicates through apassage 143 with the chamber 127 in the body 116 below the diaphragm121.

The inlet and outlet valve means 91, previously referred to, includes avalve seat 144 carried by a plate 145 below the diaphragm 131 and havinga valve port 146 leading from the outlet chamber 142 into the spacebetween the diaphragms 130 and 131. A coiled compression spring 145a isprovided beneath the plate 145 which applies a normal inward bias to thediaphragm 131 and to the outlet valve seat 144. A valve stem 147 isreciprocably mounted in a port 147a in the end member 117, which portleads from the inlet 84 to the outlet 85. The stem is normally biasedinwardly by a coiled compression spring 148 which seats in a plug 149 inthe end member 117 and acts inwardly on a spherical valve head 150 tobias the same against an inlet valve seat 151.

As previously indicated, the position sensing pneumatic control devicefunctions to regulate the output signal pressure at the port 85 to avalue which is proportional to sensed movement. Accordingly, the outerend 93 of the shaft 92, in the illustrative embodiment, has mountedthereon the sheave or roller 17 of the tensiometer'lS which is engagedby the cable or line L, to effect rotation of the shaft 92 in responseto relative movement between the line L and the sensing device. Movementof the line L is transmitted to the shaft 92 to effect rotation of thelatter in one direction or the other depending upon the direction ofmovement of the line L. It is apparent that rotation of the shaft 92 inone direction or the other will impose more or less compression on thespring 98 to provide more or less force acting on the piston means 89which will either cause the nozzle seat 137 to close the nozzle 136 orto open the nozzle 136 for communication with the chamber 127, and hencethe discharge or signal output port 85. Such spring force is opposed bythe pressure of air in the chamber 127 acting on the cross-sectionalarea of the piston 115 and the pressure of fluid in the chamber 126acting on the effective area of the piston 107. Thus, the fluid admittedthrough the port 86 to the chamber 126 may be supplied from a remote setpoint to quickly and easily calibrate the motion sensor, so that thesignal output pressure is at a desired level, less than the inputpressure, under the conditions that the shaft 92 is in the neutral ornon-moving condition.

With the foregoing details in mind, the operation of the motion sensoris such that the spring 98 is operative to apply a variable force in adirection tending to move the piston means 89 variable force in adirection tending to move the piston means 89 downwardly. Opossingtheforce derived from the actuator means is the force derived from theapplication of pressure from a remote set point to the bias orcalibrating chamber 126, which pressure is effective over the area ofthe enlargement 125 of the piston means 89 to provide a force tending tomove the piston means 89 upwardly. Also providing a force tending tomove the piston means 89 upwardly is the pressure in the piston chamber127 which acts upon the piston 115 of the piston means 89, the otherside of the piston 115 being exposed to the atmosphere in the chamber128.

The effective signal outlet pressure in the piston chamber 127 is afunction of the reduction in the inlet pressure caused by the passage ofair from the inlet 84 through the flow restrictor 140 into the pilotpressure chamber 134 and the reduction in pressure resulting from thepassage of air from the pilot pressure chamber 134 through the orificemeans 136, as indicated by the arrows, into the piston chamber 127. Whenthe device is in the condition shown in F IG. 4, the effective signaloutlet pressure at the outlet 85 is the same as that in the pistonchamber 127, and under the condition shown the pressure drop from theinlet 84 to the outlet 85 will remain constant, unless theforce derivedfrom the actuator means 88 is varied or the force derived from theremote set point pressure is varied.

Assuming that the force derived from the actuator means tending to shiftthe piston means 89 downwardly is reduced, the net force acting on thepiston means will cause the piston means to move upwardly, allowinggreater flow from the pilot pressure chamber 134 into the piston chamber127. Such action will result in an instantaneous decrease in the pilotpressure in the chamber 134. As a consequence, pressure applied to thediaphragm 131 and the force of the spring 145a will move the exhaustvalve seat 144 upwardly and off of the end of the valve stem 147, toallow the exhaust of fluid pressure from the outlet chamber 142 and thepiston chamber 127 through exhaust port 87, until the device againassumes the condition shown in FIG. 4 at which the exhaust valve port146 is again closed. At this time, the pressureat the outlet will againbe stabilized at a value determined by the fluid pressures acting on theactuator means 88 and the decreased spring force of the spring 98. Alarger volume of air will flow past the orifice closure 137, and thesignal outlet pressure will be at a lower value. 0

Assuming that the force derived from the actuator means tending to movethe piston means 89 downwardly is increased, overcoming the effect ofthe signal outlet pressure in the chamber 127, then the orifice closuredisc 137 will engage the end of the orifice means 136, thereby'shuttingoff the passage of air from the pilot pressure chamber 134 into thepiston chamber 127. Under these circumstances, the pilot pressure in thepilot chamber 134 will build up, forcing the diaphragm and the diaphragm131 downwardly, thereby unseating the valve 150, so that inlet pressurewill transfer through port 147a of the inlet-outlet valve 91, resultingin an increase in the signal outlet pressure in the outlet chamber 142and in the piston chamber 127 which will be effective to again conditionthe apparatus as shown in FIG. 4, so that the pressure at the outlet 85again remains constant, but greater.

It will now be understood that variation of the remote set pointpressure in the chamber 126 will have the same effect as variation offorce derived from the actuator means. in other words, as the remote setpoint pressure is increased, the force tending tomove the piston means89 upwardly will also be increased, but if the remote set point pressureis decreased, the force tending to move the piston means 89 upwardlywill be decreased. The supply of air to the chamber 126 through the port86 is shown in FIG. 20, as being via a conduit 860 leading from asuitable valve 86!: which controls the pressure derived from a sourceconduit 860 which leads from a suitable pressure source, not shown. Theoutlet port 85 is in communication with a conduit 85a which leads to thecomputer means 27, now to be described.

This computer means 27, as seen in FIG. 3, comprises a support 200adapted to be mounted at a suitable location. Carried by the support 200is an end cup 201 having a marginal flange 202 for connecting the cup201 with an assembly which comprises a stack of discs 203, 204, 205, 206and 207 and a body 208, all connected at the outer peripheries by asuitable number of tie bolts, one of which is shown at 209. The disc 203includes a rigid central section 203' and a flexible annular diaphragm203" supporting the central section 203' and a flexible annulardiaphragm 203" supporting the central section 203' within the disc 203.Similarly, each of the discs 204, 205, 206 and 207 comprises a rigidcentral section 204 to 207' and an annular diaphragm 204" to 207".Intermediate, the discs 203 to 207 are annular, outer peripheral spacers210 and central spacers 211. The outer spacers 210 are connected in theassembly by the tie bolts 209. The central spacers 211 areinterconnected at the respective central sections 203' to 207' by a pin212 having a head 213 at its lower end and a nut 214 at its upper endfor clamping the piston sections and central spacers together.

Fluid under pressure, say air, is supplied to the computer means 27above and below the stack of diaphragms and between the diagrams fromvarious sources, whereby to provide an output pressure signal which is afunction of the various input signals and the constant force of anadjustable coiled spring K which is disposed in the cap 201 and seats,at one end, on a seat 215 above the disc section 203' and at the otherend on a spring seat 216 carried by an axially shiftable adjuster pin217. The pin 217 is shiftable by an adjuster screw 218 threaded in a nut219 which is suitably affixed to the support 200. Below the disc 207 isanother coiled spring K which seats at one end in a seat 208 and engagesat its other end beneath the disc section 207 in opposition to thespring K. Thus, the spring K is adjustable to provide a selected forceon the stacked disc sections 203 to 207, determined by the relationshipbetween springs K and K.

Air pressure is supplied to a chamber P1 in the cup 201, from theposition sensor 16 via conduit 85a, by suitable means, such as an inletfitting 220, to provide a downward force on the effective piston area ofthe central section 203' of disc 203. In order to increase the magnitudeof the force derived from air pressure supplied to the computer 27 fromthe position sensor 16 via conduit 85a, a branch conduit 85b leads to achamber P2 defined between the diaphragms 203" and 204", say through apressure inlet 221, so that such pressure also acts downwardly on theeffective annular piston area of the central section 204 of the disc204, which extends radially beyond the spacer 211 thereabove.

Below the annular piston area of the disc section 204 is a chamber Rhaving an inlet 222 to which pressure fluid is supplied, as will belater described, at a value determined by the computer 27, the pressurein chamber R acting upwardly on the effective annular piston area of thedisc section 204 in opposition to the downward force derived frompressure in the chambers P1 and P2.

Between the discs 205 and 206 is defined a pressure chamber S to whichair is supplied through an inlet 223 via a conduit 260, at a pressuredetermined by the speed of rotation of the drum 13, under the control ofthe electro-pneumatic transducer 26, previously referred to. The discsection 206 provides an annular piston area projecting radiallyoutwardly of the spacer 211 thereabove, this piston area beingresponsive to pressure in chamber S to provide a downward force. Belowthe disc section 206 is another chamber T to which air is supplied via aport 224 at a pressure determined, as will be later described, by thetension on the line L. Such pressure acts upwardly on the effectiveannular piston area of the disc section 206.

Below the disc 207, and in the body 208, is a chamber X whichconstitutes an output chamber communieating with an outlet port 225 viaporting 226. The pressure in the chamber acts upwardly on the lower discsection 207, and this pressure is derived from on inlet conduit 27a(FIG. 2a) connected to an inlet port 227, under the control of thecomputer.

Interposed between the body 208 and an end member 228 having the ports225 and 227 therein, and clamped at its outer margin is a doublediaphragm assembly 229 including an upper diaphragm 230 and a lowerdiaphragm 231 spaced apart by an outer marginal spacer 232 in which isformed one or more radial outlet ports 232a, which communicate the spacebetween the diaphragms 230 and 231 with the atmosphere. In the body 208above the upper diaphragm 230 is a threaded bore having therein a nozzle236, the port through which communicates with the chamber X, and theoutlet of which is opposed by a valve head 237 suitably carried by thelower end of the stem 212. Air is supplied to the chamber 234 and thenceto the nozzle 236 from the supply port 227 through a passage 238 whichextends through the margin of the diaphragms 230 and 231 and the spacer232 and connects with a passage 239 leading into the chamber X. Disposedin the passage 239 is a flow restrictor 240 having a reduced passagetherethrough. This flow restrictor is replaceable through an opening inthe body 208 which is closed by a threaded closure plug 241. At theunderside of diaphragm 231 in the end member 228 is a chamber 241 whichcommunicates with the output port 225. The output port 225 alsocommunicates through the passage 226, previously referred to, with thechamber X in the body 208 below the piston or disc section 207'.

Inlet and outlet valve means are provided to control the admission offluid from the inlet 227 to the chamber 242 and the exhaust of suchfluid through the vent port 232a. This valve means includes a valve seat244 carried by a plate 245 below the diaphragm 231 and having a valveport 246 leading from the .outlet chamber 242 into the space between thediaphragms 230 and 231. A coiled compression spring 245a is providedbeneath the plate 245 and applies a normal upward bias to the diaphragm231 and to the outlet valve seat 244. A valve stem 247 is reciprocablymounted in a port 247a in the end member 228 which port leads from theinlet 227 to the outlet chamber 242. The stem is normally biasedinwardly by a coiled compression spring 248 which seats in a plug 249 inthe end member 228 and acts inwardly on a spherical valve head 250 tobias the same against an inlet valve seat 251.

As previously indicated, the computer means functions to regulate theoutput signal pressure at the port 225 to a value which is proportionalto;load on or position of the line L, as well as speed of the drum 13,and in addition, the computer may be adjusted to modify the outputpressure by varying either the effective constant force of spring K orthe reference set point pressure in the chamber R. Thus, as will beunderstood, the output pressure in chamber X is determined by thevarious pressures in the various chambers P1, P2, R, S and T, acting onthe various piston areas of the discs 203 to 207. The equation may bestated:

sition sensor 16 tending to close the nozzle 236, R is the.

pressure derived from a reference pressure source tending to open thenozzle 236, S is the pressure derived from the speed of the drum 13tending to close the nozzle 236, T is the pressure derived from thetension sensing means 15 tending to open the nozzle 236, and K is thespring constant.

The effective signal outlet pressure in the outlet chamber 242 is afunction of the reduction in the inlet pressure caused by the passage ofair from the inlet 227 through the flow restrictor 240 into the pilotpressure chamber 234, and the reduction in pressure resulting from thepassage of air from the pilot pressure chamber 234 through the orificemeans 236, as indicated by the arrows, into the pressure chamber X. Whenthe device is in the condition shown in FIG. 3, the effective signaloutlet pressure at the outlet 225 is the same as that in the chamber X,and, under the condition shown, the pressure drop from the inlet 227 tothe outlet 225 will remain constant, unless the force derived from anyof the position sensing means TP, the tachometer 25, or the referencepressure is varied, and, accordingly, as will be later more fullydescribed, the actuating pressure supplied to the clutch C will remainconstant.

Assuming that the force tending to shift the stacked disc sectionscauses the valve head 237 to move upwardly allowing greater flow fromthe pilot pressure chamber 234 into the chamber X, such actionwill'result in a decrease in the pilot pressure in the chamber 234. As aconsequence, pressure applied to the diaphragm 231 and the force of thespring 145a will move the exhaust valve seat 244 upwardly and off of theend of the valve stem 247 to allow the exhaust of fluid pressure fromthe outlet chamber 242 and the chamber X through exhaust port 232abetween the diaphragms 230 and 231, until the device again assumes thecondition shown in FIG, 3 at which the exhaust valve port 246 is againclosed. At this time, the pressure at the outlet 255 willagain bestabilized at a lower value, determined by the change in forces actingon the stack of disc sections 203' to 207'.

Assuming that the net force tending to move the stacked discs 203' to207 downwardly is increased, overcoming the effect of the signal outletpressure in the chamber X, then the orifice valve 237 will close theorifice means 236, thereby shutting off the passage of air from thepilot pressure chamber 234 into the chamber X. Under thesecircumstances, the pilot pressure in the pilot chamber 234 will buildup, forcing the diaphragm 230 and the diaphragm 231 downwardly, therebyunseating the valve 250, so that inlet pressure will transfer throughport 247a of the inlet-outlet valve means, resulting in an increase inthe signal outlet pressure in the outlet chamber 241 and in the chamberX, which will be effective to again condition the apparatus as shown inFIG. 3, so that the pressure drop therethrough again remains constant,but greater, since there is less flow through'the orifice means 236.

The conduit 300 leads from the outlet port 225 of the computing relay 27to the control pressure inlet 301 of a pressure controller C1 of aconventional type adapted to control the pneumatic pressure at an outlet302 suppliedfrom asuitable source (not shown) through an inlet 303,whereby, as will be later described the slip clutch C is adapted toapply a controlled constant I torque to the drum 13 which is a functionof the output signal pressure of the computer or transmitter means 27.

More particularly, the controller C1 may be Model 50 Controller of MooreProducts Co., of Spring House, Pennsylvania or a Model 2516 Controllerof Fisher Governer Company of Marshalltown, Iowa, as examples, thecontroller, generally, shown in FIG. 2b, being the latter and morespecifically illustrated in Bulletin D-2506A of that company.

The controller C1 is supplied a reference pressure at an inlet 304 froma conduit 305 connected to a source (not shown) by a regulator valve306, the same reference pressure being supplied to the reference chamberR of the computer or transmitter means 27. This reference pressure isadmitted to a bellows 307 of the controller which cts downwardly on aplate 308. Pressure supplied to the inlet 301 from the computer 27causes an increase in acts in a bellows 309 which is opposed to thebellows 307 and acts upwardly on the plate 308. The position of theplate 308 relative to a nozzle 310 to which controlled fluid pressure issupplied from the source inlet 303, is determined by the difference inpressures in the bellows 307 and 309. If the output pressure from thecomputer means 27 increases, the pressure increases in bellows 309causing the plate 308 to move closer to the nozzle 310, restricting flowthrough the nozzle to cause an increase in the pressure in a chamber 311 ofa control valve 312, causing an increased downward force on adiaphragm assembly comprising spaced diaphragms 313 and 314, whichcarries a valve seat 315, the passage through which communicates withthe atmosphere through a port 316 between the diaphragms 313 and 314.The valve seat 315 engages and pushes downwardly, under thecircumstances now being described, on an inlet and outlet valve having ahead 317 for closing the exhaust passage through the valve seat 315 anda head 318 which is moved away from a seat 319 to allow increased supplypressure into the valve outlet chamber 320 which acts on the diaphragm314 until the valve seat 315 is again moved upwardly to allow returnupward movement of the inlet-outlet valve head 318 towards its seatvDuring the same time, pressure is increasing in the chamber 320, suchpressure is supplied to the outlet 302, and, thus, to the clutch C, aswell as to an adjustable proportioning valve 321 and, depending on theadjustment of the latter, to an adjustable re-set control valve 322which controls the build up of pressure in a bellows 323. This bellows323 acts downwardly on the plate 308 tending to move the latter awayfrom the nozzle 310 to decrease pressure at the outlet 302 and incontrol valve chamber 320, and is opposed by the upward action of abellows 324 to which pressure is supplied from the valve 322 at a slowerrate, depending on the adjustment of the valve 322, until the plate 308is moved toward the nozzle to again increase pressure at the outlet 302and in the valve chamber 320.

If a chamge in the system'causes a decrease in pressure at the inlet 301to the controller C1, then, the reverse action will occur in thecontroller, the tendency being in either case to attempt to return to apreestablished, constant pressure at the outlet 302 which pressure is afunction of the outlet pressure'from chamber X of the above-describedcomputer means.

The outlet pressure from the controller means C l is supplied via aconduit 325 to cause actuation of the clutch C, but preferably a typicalbooster 326 is employed, whereby the actual pressure source (not shown)for the clutch includes an inlet to the booster 326 from a relativelyhigh pressure source, and the pressure in conduit 32S acts on the usualpilot valve of the booster, so that the outlet 328 of the booster is ata greater pressure than the signal pressure from the controller C1. Inaddition, is preferred that a selector valve 329 be provided, so thatthe air connector of the clutch C may be connected either to the boosteroutlet 328 or, alternatively, to a separate source conduit 330 includinga manualcontrol valve for operating the clutch C independently of thecontrol system.

A second controller means C2 is employed, as previously indicated, tovary the pressure supplied to the chamber T of the computer ortransmitter means 27, as a function of line tension, and, thus, to varythe output signal pressure from the computer according to the aboveequation for the pressure of the chamber X.

Accordingly, leading from the hydraulic load cell 24 of the tensiometer15 of the sensing means TP, to the controller means C2 is a conduit 331through which a hydraulic pressure signal depending upon load or tensionof the line L is transmitted to the controller C2 to control thepneumatic pressure supplied to the controller outlet 332 from an inlet333. This controller C2, for example, may be the Model 4151 remote setproportional controller or transmitter of the Fisher Governor Company,as illustrated in Bulletin D415OC.

In the illustrative controller C2 is a hydraulic pressure responsivemeans in the form of a Bourdon tube 334, an increase in pressure inwhich forces a plate 335 toward an exhaust nozzle 336 of the controlvalve means 337, and a decrease in pressure in which moves the plate 335away from the nozzle 336 to vary the pressure in the valve chamber 338as the sensed hydraulic pressure signal is varied to cause a decrease orincrease in the outlet pressure at outlet 333 and in the chamberT of thecomputer means 27, whereby the net result is the application ofapressure to clutch C dependent upon the tension on line L.

The control valve means 337 is similar to the control valve means 312previously described, and includes a diaphragm assembly comprising adiaphragm 339 exposed to pressure in the chamber 338 derived from theinlet 333, and a diaphragm 340 exposed to pressure in the valve chamber341 which communicates with the outlet 332. This diaphragm assemblycarries a valve seat 342, the passage through which communicates withthe atmosphere through a port 343. A combined inlet and outlet valve hasa head 344 engageable with the seat 342 to prevent exhaust of pressurefrom chamber 341 and a head 345 engageable with a seat 346, the passagethrough the latter communicating between the inlet 333 and the chamber341.

Thus, if pressure in the Bourdon tube 334 is increased, due to anincrease in tension on line L, the exhaust of pressure from chamber 338will be restricted, causing an increase in pressure acting on thediaphragm 339, so that the valve seat 342 will engage valve head 344,preventing exhaust of air from the chamber 341 through the exhaust port343, and, at the same time, the valve head 345 will be moved off of itsseat, allowing an increase in pressure in chamber 341 which tends toreturn the diaphragm to'its original position.

Such increased pressure in the chamber 341 is conducted to an adjustablevalve 347, and thence to a be]- lows 349 which acts on the plate 335 tomove the same away from the nozzle 336 to effectively reduce thepressure in the chamber 338. Resisting such movement of the plate 335 isa bellows 350 having an inlet 351 to which a set point pressure issupplied from a remote point, such as a regulator valve 352 to whichfluid is supplied from a suitable source (not shown), as for example,the same source as supplies reference pressure to the controller C1 andthe computer or transmitter means 27.

Reduction in hydraulic signal pressure from the tensiometer 15 to thecontroller C2 will cause the plate 335 to move away from the nozzle 334and a reduction in pressure in the control valve chamber 338, resultingin opening of the passage through valve seat 342 and reduction in thesignal at outlet 332 and computer chamber T. This is to say that in thelatter case, the operation of the controller is the reverse of thatdescribed above, as will be understood without need for furtherexplanatlon.

For convenience, a gauge panel G is preferably provided, as seen in FIG.2b, whereby to indicate the effective pressures determined by theposition sensing means 16, the speed responsive means 26, and the linetension or load responsive means 15, as well as the reference pressure,the set-point pressure for controller C2, and the ultimate clutchactuating pressure supplied to the slip clutch C, respectively, suchgauges being designated by the legends POS., REF, SPEED, LOAD,SET-POINT, and CLUTCH.

The POS, gauge is connected to the output of the position sensing means16 by a conduit 400 which joins with the conduit 85a leading to thecomputer chambers P1 and P2. The REF. gauge is connected by a conduit401 to the conduit 305 which leads to both the inlet 304 of controllerC1 and the chamber R of the computer 27. The SPEED gauge is connected bya conduit 402 with the conduit 26a leading to the chamber S of thecomputer 27 from the drum speed responsive electro-pneumatic transducermeans 26. The LOAD gauge is connected by a conduit 403 and a conduit 404with the outlet 332 from the load or tension responsive controller meansC2 and the chamber T of the computer 27. The SET-POINT gauge isconnected by a conduit 405 between the set-point inlet 351 of the loadresponsive controller C2 and the supply regulator valve 352. TheCLUTCl-l" gauge is-connected by a conduit 406 with the air inletconnector of the clutch C and the outlet of the selector valve 329.

From the foregoing, it is believed that the operation of the presentinvention clearly involves the controlling of the slip clutch drivemeans for the drum 13 to apply a tension to the line L controlled suchthat the tension is maintained substantially constant below a valueestablished by the load SET-POINT pressure, but the air pressure supplyto the clutch is, in the automatic mode, controlled by changes in load'or position sensed by the sensing means TP, whereby under added load,the line will be stripped from the drum in a predetermined ratio of feetof line to increased load until the line tension resumes the establishedvalue, and the line will then be wound on the drum to reposition theload relative to the towing vessel. The speed and extent of linemovement in either direction is sensed by the speed responsive means 25,26 and the position sensing means 16 to vary the clutch operation tomaintain a pre-established tension on the line to an establishedposition at a controlled rate.

Thus, under all conditionsencountered by a towed vessel or barge B beingtowed by a towing vessel V, such as waves and wind or other forces, thebarge may be positioned closely to the towing vessel without fear ofparting the line L.

If it is assumed that a speed reference signal of 9 p.s.i. is suppliedto the computer chamber S when the drum is static, the referencepressure of 5 p.s.i. is supplied to the inlet 304 of controller Cl andto the chamber R of the computing relay 27, the controller C2 supplies aload orv tension reference pressure to the chamber T of 9 psi. at apredetermined line tension, and the position sensor 16 supplies aposition signal of 5 p.s.i. to the chambers P1 and P2 of the computer27, then the equation representing the computer output pressure is Underthese conditions, the output signal to the inlet 301 of controller C1from the computing relay is the same as the reference input pressuresignal at the inlet 304, and, therefore, the clutch actuating signalpressure transmitted to the booster 326 remains constant, and the linetension caused by the torque transmitted by the clutch C remainsconstant.

Now, if the load on line L decreases, due to the tendency of the towedvessel and the towing vessel to move towards one another, for example,so that the load signal pressure derived from the load sensor and thecontroller C2 is reduced to 8 p.s.i., then the equation reads:

Under these conditions, the output signal to the inlet 30] of thecontroller Cl is 6 p.s.i., but the reference pressure is 5 psi,resulting in an increase in the pressure inthe chamber 311 of thecontrol valve 312 and a resultant increase in the pressure in the outlet302 of the controller Cl and in the pressure applicable to the clutchactuator to tend to wind in the line. Conversely,

- if the load on the line increases, the clutch actuating signalpressure will be decreased Under these conditions, however, lineposition changes are reflected in the pressure signal derived from theposition sensor operated controller C2, so that as the line moves in orout the effective pressure in the chamber P1 and P2 of the computer 27is varied by the position sensing means 16, and the effective pressurein the chamber S of the computer is varied by the speed of drummovement, resulting in a control system which is capable of maintainingposition of the towed vessel, under constant line tension conditions,but enables the line to be stripped from the drum in a predeterminedratio of feet of line to increased load on the line above the set-point.Indeed, the system can be at equilibrium when subjected to loads on theline different than the load which the system is adjusted for by theset-point. The system automatically returns the line to a preestablishedposition when the line is subjected to the pre-established tension.

I claim:

1. ln a winch system including a winch drum having a line thereonconnectable to a load, drive means for driving said drum to wind saidline on said drum, to hold said line, and to allow said line to bestripped away from said drum, said drive means including acontinuouslyoperable slip clutch having continuously variable actuatormeans operable to adjust the torque transmitted to said drum by saiddrive means, settable control means for establishing a predeterminedline position at a preselected line tension, said control meanscomprising: line position sensing means responsive to the deviation ofsaid line away from said predetermined line position for producing anoutput signal proportional to saiddeviation, line tension sensing meansresponsive to the tension in aid line for producing an output signalproportional to the deviation of said tension from said preselectedtension, said control means including computer means comprising meansfor receiving both said output signals and producing a continuouslyvariable clutch control signal which is a function of the integration ofsaid output signals, and means for varying said actuator means as afunction of said clutch control signa] to adjust said actuator means forcausing said line to be stripped away from, held on, or returned to saiddrum in response to said clutch control signal to continuously controlthe deviation of said line from said predetermined line position inproportion to said deviation of the tension in said line.

2. In a winch system as defined in claim 1, speed sensing means operableby said drum, said control means including means operable by said speedsensing means to adjust said actuator means and control the speed ofmovement of said drum.

3. In a winch system as defined in claim 1, said actuator meanscomprising an air pressure responsive device, a source of air connectedto said device, and said control means varying the supply of air to saiddevice from said source.

4. In a winch system as defined in claim 1, said control meanscomprising means for producing a variable air signal pressure to adjustsaid'actuator means.

5. In a winch system as defined in claim 4, speed responsive meansoperable by said drum to adjust said air signal pressure to limit thespeed of movement of said drum.

6. In a winch system as defined in claim 1, said line tension sensingmeans comprising tensiometer means engaged with said line, said positionsensing means engaged with said line, and said control means comprisingcomputer means for receiving said output signals and producing a'clutchcontrol signal at a constant value determined by the difference betweensaid output signals.

7. In a winch system as defined in claim 6, speed responsive means toproduce an output signal determined by the speed of movement of saidline, said computer means receiving said output signal of said speedresponsive means and being operable to produce a clutch control signaldetermined by the difference between the sum of said output signal ofsaid position sensing means and said output signals of said speedresponsive means, and the output signal of said tensiometer means.

8. In a winch system as defined in claim 1, said line tension sensingmeans comprising tensiometer means engaged with said line, said positionsensing means engaged with said line, said control means comprisingcomputer means for receiving said output signals and producing a clutchcontrol signal at a constant value determined by the difference betweensaid output signals, and speed responsive means operable upon winding ofline on said drum and stripping of line from said drum to produce aspeed responsive output signal, said computer means receiving the latteroutput signal and adding the same to said position control signal inproducing said clutch control signal.

9. In a winch system as defined in claim 1, said line tension sensingmeans comprising tensiometer means engaged with said line, said positionsensing means engaged with said line, and said control means comprisingcomputer means for receiving said output signals and producing a clutchcontrol signal determined by the difference between said output signals,said control means including a pressure controller operable in re sponseto said output signal of said tensiometer means to maintain said outputsignal determined by the load on said line at a constant value.

10. In a winch system as defined in claim 1, said line tension sensingmeans comprising tensiometer means engaged with said line, said positionsensing means engaged with said line, and said control means comprisingcomputer means for receiving said output signals and producing a clutchcontrol signal determined by the difference between said output signals,said control means including a pressure controller operable in responseto said output signal of said tensiometer means to maintain said outputsignal determined by the load on said line at a constant value, andspeed responsive means operable upon winding and unwinding ofline onsaid drum to produce a speed responsive output signal, said computermeans receiving the latter output signal, said speed responsive outputsignal being added to said output signal from said position sensingmeans by said computer means in producing said clutch control signal.

11. In a winch system as defined in claim 1, said actuator meanscomprising an air pressure responsive device, a source of air connectedto said device, said control means varying the supply of air to saiddevice from said source, said control means comprising a pressurecomputer for receiving variable input pressure signals representative ofload on said line, the deviation of said line, and a reference pressure,and said computer producing an output pressure signal determined by theequation X 2? R T,

where X is the computer output signal pressure, P is the input pressuresignal determined by the deviation of said line, R is the referenceinput pressure signal, and T is the input signal pressure determined byload on said line, said tension sensing means sensing the load on saidline and said position sensing means sensing the deviation of said lineand supplying said variable input pressure signals to said computermeans representative of load on said line and the position of said line,and means for supplying a selected reference signal pressure to saidcomputer means.

12. In a winch system as defined in claim 11, said computer meanscomprising a control valve assembly having an air inlet, an air outlet,and an exhaust port, and valve means for controlling the flow of airfrom said inlet to said outlet and said exhaust port to maintain saidoutput pressure signal substantially constant at a selected pressure.

13. In a winch system as defined in claim 1, said clutch actuator meanscomprising an air pressure responsive device, a source of air connectedto said device, said control means varying the supply of air to saiddevice from said source, said control means comprising a pressurecomputer for receiving variable input pressure signals representative ofload on said line, the deviation of said line, and a reference pressure,and said computer producing an output pressure signal determined by theequation where X is the computer output signal pressure, P is the inputpressure signal determined by the deviation of said line, R is thereference input pressure signal, and T is the input signal pressuredetermined by load on said line, said tension sensing means sensing theload on said line and said position sensing means sensing the deviationof said line and supplying said variable input pressure signals to saidcomputer means representative of load on said line and the position ofsaid line, means for supplying a selected reference signal pressure tosaid computer means, and controller means for receiving the computeroutput signal and variably transmitting a constant output signal tocontrol said clutch of a magnitude determined by said computer outputsignal.

14. In a winch system as defined in claim 1, said clutch actuator meansbeing pneumatically operable, said line tension sensing means comprisinghydraulic load sensing means for producing a hydraulic pressure signaldetermined by the load on said line, controller means having an airinlet, an air outlet, and control valve means operable by said hydraulicpressure signal to cause a constant output pressure signal at saidoutlet, said sensing means also comprising pneumatic sensing meansoperable in response to deviation of said line and including an airinlet, an air outlet, and control valve means operable to cause aconstant output pressure signal at the latter outlet, additionalcontroller means having an air inlet, an air outlet, and control valvemeans operable to cause a constant output pressure signal at thelast-mentioned outlet, pneumatic computer means having an air inlet, anair outlet and control valve means for maintaining a constant outputpressure signal at the outlet of said computer means at a pressuredetermined by a comparison of said output pressure signals from saidcontrollers, and means for put pressure signal from said computer means.

Patent No.

Inventor(s) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION3,801,071 Dated April 2, 1974 Charles D. Barron It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column Column Column [SEAL] line 7, "to" should be --at--.

line 40, "played" should be --payed--.

line 18, after "1970" insert now U.S. Patent No.

3,648,814, issued March 14, l972--.

line 6, "117" should be --l07--.

line 7, "107" should be --ll5-.

line 5, "X" should be --234--.

line 18, "145a" should be --245a--.

line 23, "333" should be --332--. 1

Signed and Scaled this Tenth Day Of October 1978 A ttest:

DONALD W. BANNER RUTH C. MASON Attesting Officer Commissioner of Patentsand Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3, 01,071 Dated April 2, 19'!- Inventor(s) Charles Barron Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Front Page, Assignee: "Byran Jackson, Inc. should read Byron JacksonInc. Long Beach, Calif.

Signed and Sealed this A rtest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (ummisxioner ofPare'ntsand Trademarks

1. In a winch system including a winch drum having a line thereonconnectable to a load, drive means for driving said drum to wind saidline on said drum, to hold said line, and to allow said line to bestripped away from said drum, said drive means including a continuouslyoperable slip clutch having continuously variable actuator meansoperable to adjust the torque transmitted to said drum by said drivemeans, settable control means for establishing a predetermined lineposition at a preselected line tension, said control means comprising:line position sensing means responsive to the deviation of said lineaway from said predetermined line position for producing an outputsignal proportional to said deviation, line tension sensing meansresponsive to the tension in aid line for producing an output signalproportional to the deviation of said tension from said preselectedtension, said control means including computer means comprising meansfor receiving both said output signals and producing a continuouslyvariable clutch control signal which is a function of the integration ofsaid output signals, and means for varying said actuator means as afunction of said clutch control signal to adjust said actuator means forcausing said line to be stripped away from, held on, or returned to saiddrum in response to said clutch control signal to continuously controlthe deviation of said line from said predetermined line position inproportion to said deviation of the tension in said line.
 2. In a winchsystem as defined in claim 1, speed sensing means operable by said drum,said control means including means operable by said speed sensing meansto adjust said actuator means and control the speed of movement of saiddrum.
 3. In a winch system as defined in claim 1, said actuator meanscomprising an air pressure responsive device, a source of air connectedto said device, and said control means varying the supply of air to saiddevice from said source.
 4. In a winch system as defined in claim 1,said control means comprising means for producing a variable air signalpressure to adjust said actuator means.
 5. In a winch system as definedin claim 4, speed responsive means operable by said drum to adjust saidair signal pressure to limit the speed of movement of said drum.
 6. In awinch system as defined in claim 1, said line tension sensing meanscomprising tensiometer means engaged with said line, said positionsensing means engaged with said line, and said control means comprisingcomputer means for receiving said output signals and producing a clutchcontrol signal at a constant value determined by the difference betweensaid output signals.
 7. In a winch system as defined in claim 6, speedresponsive means to produce an output signal determined by the speed ofmovement of said line, said computer means receiving said output signalof said speed responsive means and being operable to produce a clutchcontrol signal determined by the difference between the sum of saidoutput signal of said position sensing means and said output signals ofsaid speed responsive means, and the output signal of said tensiometermeans.
 8. In a winch system as defined in claim 1, said line tensionsensing means comprising tensiometer means engaged with said line, saidposition sensing means engaged with said line, said control meanscomprising computer means for receiving said output signals andproducing a clutch control signal at a constant value determined by thedifference between said output signals, and speed responsive meansoperable upon winding of line on said drum and stripping of line fromsaid drum to produce a speed responsive output signal, said computermeans receiving the latter output signal and adding the same to saidposition control signal in producing said clutch control signal.
 9. In awinch system as defined in claim 1, said line tension sensing meanscomprising tensiometer means engaged with said line, said positionsensing means engaged with said line, and said control means comprisingcomputer means for receiving said output signals and producing a clutchcontrol signal determined by the difference between said output signals,said control means including a pressure controller operable in responseto said output signal of said tensiometer means to maintain said outputsignal determined by the load on said line at a constant value.
 10. In awinch system as defined in claim 1, said line tension sensing meanscomprising tensiometer means engaged with said line, said positionsensing means engaged with said line, and said control means comprisingcomputer means for receiving said output signals and producing a clutchcontrol signal determined by the difference between said output signals,said control means including a pressure controller operable in responseto said output signal of said tensiometer means to maintain said outputsignal determined by the load on said line at a constant value, andspeed responsive means operable upon winding and unwinding of line onsaid drum to produce a speed responsive output signal, said computermeans receiving the latter output signal, said speed responsive outputsignal being added to said output signal from said position sensingmeans by said computer means in producing said clutch control signal.11. In a winch system as defined in claim 1, said actuator meanscomprising an air pressure responsive device, a source of air connectedto said device, said control means varying the supply of air to saiddevice from said source, said control means comprising a pressurecomputer for receiving variable input pressure signals representative ofload on said line, the deviation of said line, and a reference pressure,and said computer producing an output pressure signal determined by theequation X 2P - R - T, where X is the computer output signal pressure, Pis the input pressure signal determined by the deviation of said line, Ris the reference input pressure signal, and T is the input signalpressure determined by load on said line, said tension sensing meanssensing the load on said line and said position sensing means sensingthe deviation of said line and supplying said variable input pressuresignals to said computer means representative of load on said line andthe position of said line, and means for supplying a selected referencesignal pressure to said computer means.
 12. In a winch system as definedin claim 11, said computer means comprising a control valve assemblyhaving an air inlet, an air outlet, and an exhaust port, and valve meansfor controlling the flow of air from said inlet to said outlet and saidexhaust port to maintain said output pressure signal substantiallyconstant at a selected pressure.
 13. In a winch system as defined inclaim 1, said clutch actuator means comprising an air pressureresponsive device, a source of air connected to said device, saidcontrol means varying the supply of air to said device from said source,said control means comprising a pressure computer for receiving variableinput pressure signals representative of load on said line, thedeviation of said line, and a reference prEssure, and said computerproducing an output pressure signal determined by the equation X 2P -R - T where X is the computer output signal pressure, P is the inputpressure signal determined by the deviation of said line, R is thereference input pressure signal, and T is the input signal pressuredetermined by load on said line, said tension sensing means sensing theload on said line and said position sensing means sensing the deviationof said line and supplying said variable input pressure signals to saidcomputer means representative of load on said line and the position ofsaid line, means for supplying a selected reference signal pressure tosaid computer means, and controller means for receiving the computeroutput signal and variably transmitting a constant output signal tocontrol said clutch of a magnitude determined by said computer outputsignal.
 14. In a winch system as defined in claim 1, said clutchactuator means being pneumatically operable, said line tension sensingmeans comprising hydraulic load sensing means for producing a hydraulicpressure signal determined by the load on said line, controller meanshaving an air inlet, an air outlet, and control valve means operable bysaid hydraulic pressure signal to cause a constant output pressuresignal at said outlet, said sensing means also comprising pneumaticsensing means operable in response to deviation of said line andincluding an air inlet, an air outlet, and control valve means operableto cause a constant output pressure signal at the latter outlet,additional controller means having an air inlet, an air outlet, andcontrol valve means operable to cause a constant output pressure signalat the last-mentioned outlet, pneumatic computer means having an airinlet, an air outlet and control valve means for maintaining a constantoutput pressure signal at the outlet of said computer means at apressure determined by a comparison of said output pressure signals fromsaid controllers, and means for supplying air to said clutch actuatormeans at a pressure determined by said output pressure signal from saidcomputer means.
 15. In a winch system as defined in claim 14, speedresponsive means operable in response to rotation of said drum toproduce an air pressure signal determined by the speed of said drum,said computer means receiving the last-mentioned pressure signal toadjust the output pressure signal from said computer means.